times2

Usage

#include <sys/times.h>

Library

Standard C library (libc, -lc)

Overview

times() stores the current process times in the struct tms that buf points to. The struct tms is as defined in <sys/times.h>:

struct tms {
    clock_t tms_utime;  /* user time */
    clock_t tms_stime;  /* system time */
    clock_t tms_cutime; /* user time of children */
    clock_t tms_cstime; /* system time of children */
};

The tms_utime field contains the CPU time spent executing instructions of the calling process. The tms_stime field contains the CPU time spent executing inside the kernel while performing tasks on behalf of the calling process.

The tms_cutime field contains the sum of the tms_utime and tms_cutime values for all waited-for terminated children. The tms_cstime field contains the sum of the tms_stime and tms_cstime values for all waited-for terminated children.

Times for terminated children (and their descendants) are added in at the moment wait(2) or waitpid(2) returns their process ID. In particular, times of grandchildren that the children did not wait for are never seen.

All times reported are in clock ticks.

Return value

times() returns the number of clock ticks that have elapsed since an arbitrary point in the past. The return value may overflow the possible range of type clock_t. On error, (clock_t) -1 is returned, and errno is set to indicate the error.

Errors

EFAULT

tms points outside the process's address space.

Versions

On Linux, the buf argument can be specified as NULL, with the result that times() just returns a function result. However, POSIX does not specify this behavior, and most other UNIX implementations require a non-NULL value for buf.

Notes

The number of clock ticks per second can be obtained using:

sysconf(_SC_CLK_TCK);

Note that clock(3) also returns a value of type clock_t, but this value is measured in units of CLOCKS_PER_SEC, not the clock ticks used by times().